The present invention relates to tonneau cover attachment apparatus having a rear bar or end plate and end plate engagement members cooperating to impart tension to a flexible cover attached to the end plate when the end plate pivots into or is positioned in a closed or fixed stretching position; particularly a tonneau cover attachment apparatus having an end plate engagement member or members having integrally incorporated fastening elements which are functionally stronger than other engagement elements having other mechanisms for engagement.
Numerous protective covers for preventing rain, debris and wind from damaging or disrupting the contents of a pickup truck bed are currently available. Generally, the covers are made of some sort of fabric, often coated with a polymeric material, which is detachably fastenable to a rigid frame so as to enclose and protect a given area. The covering materials used are generally stretchable to the extent that once they are in a position, they are pulled taut and then attached to the frame by numerous methods such as snaps, grommets, or hook-and-loop fasteners and stretcher bars.
The use of hook-and-loop type fasteners and stretcher bars to fasten a cover to a frame structure forms the subject matter of U.S. Pat. Nos. 5,076,338 (""338 patent) and 5,174,353 (""353 patent) issued to Steven Schmeichel et al., the disclosures of which are incorporated herein by reference.
In the Schmeichel et al. patents, an edge portion of a covering fabric is attached to a generally L-shaped end plate or stretcher bar. The end plate is provided with a peak or crest which pivotally contacts ends of the frame structure as the end plate is rotated into a fixed, stretching position. As the end plate rotates into the fixed, stretching position, an enlarged ridge of the end plate is either captured by a spring loaded lock element as depicted in a first embodiment, or engages and deflects a biased pawl element as depicted in a second embodiment. After the enlarged ridge passes the lock or pawl element, the lock or pawl element springs back to it""s undeflected state thereby maintaining the end plate in the fixed, stretching position. In order to move the end plate out of the fixed stretching position, the biasing force of the lock or the pawl element must be overcome. In the first embodiment, this biasing force may be overcome by the movement of the enlarged ridge as the end plate is pivoted out of the fixed stretching position. In the second embodiment, deflection of the pawl is best accomplished by manipulating a release member which projects from a portion of a latching member, or by opening the tailgate and manually disengaging the pawl from the enlarged ridge.
Although the Schmeichel et al. patents teach a number of significant improvements over the prior art, there are several limitations of the prior art, which are addressed and improved upon by the present invention.
One limitation of the first embodiment of the Schmeichel et al. patents, as depicted, is that the L-shaped lock member, by virtue of it""s resilient nature, merely imparts a dynamic force, which tends to maintain the end plate in the fixed stretching position. This force, however, can be overcome by the action of the enlarged ridge as it moves past the inclined portion of the L-shaped lock. Thus, the L-shaped lock does not function as a lock in a conventional sense.
A limitation of the second embodiment of the Schmeichel et al. patents is in the location and construction of the lock element. As depicted, the lock element comprises a pawl element, which is attached to one end of an elongated leaf spring. The other end of the leaf spring is attached to a connector, which in turn is connected to a side rail of the support frame structure. While this embodiment functions to lock the end plate and support frame structure in the fixed stretching position, it would appear that absent support, the pawl element may be forcibly disengaged and/or damaged by forcible movement of the end plate out of the fixed, stretching position.
Another limitation of the second embodiment of the Schmeichel et al. patents is that the end plate may be disengaged from the lock member by a person with knowledge of the location of the release member.
A limitation common to both the first and second embodiments of the Schmeichel et al. patents regards the attachment point and the design of the engagement member (or strike) which engages the end plate. As depicted in the drawings the strike is attached to the frame structure by a fastening element located a substantial distance from the inclined portion of the strike. This allows the strike to be flexed or bent upwardly in reaction to the stress forces exerted on the strike when the end plate is pivoted into and out of the fixed stretching position. Repeated flexure and/or bending may result in loosening and/or premature failure of the strike. Additionally, the strike includes a relatively thin lip portion which extends beyond the body of the strike and which rotatingly contacts the end plate as it is pivoted into and out of the fixed stretching position. This lip portion is subject to high amounts of stress and is subject to flexure and/or bending which may lead to premature failure.
Another limitation common to both the first and second embodiments of the Schmeichel et al. patents is in the attachment of the support frame about the perimeter of a cargo box of the vehicle. In Schmeichel et al., a support frame is attached to an inner side wall by a C-shaped clamp. The effectiveness of the clamp may, however, become compromised by overtightening the clamping bolt and may lead to deformation and/or failure the body of the clamp. Additionally, due to the tapered vertical attachment portion of the frame support, there is a tendency for the clamp to become dislodged from the clamping position.
The present invention provides improvements which address these and other limitations associated with the prior art.
The present invention relates to a tonneau cover apparatus for attaching and locking a flexible cover about a cargo box of a vehicle such as a pickup truck. The apparatus preferably includes a support frame, which is removably attached about the perimeter of the cargo box of the vehicle by at least one clamp. The flexible cover is attached to the support frame and to an end plate. The end plate is configured to pivotally engage an end plate engagement member, which is attached to the support frame. As the end plate pivots about the end plate engagement member to a fixed stretching position, the flexible cover is suitably stretched or tensed. In preferred embodiments, the end plate is releasably retained in the fixed stretching position by a latching member which is attached to the support frame and/or by a locking member which is slidingly attached to the end plate and which may be operatively connected to the end plate. A side bar securing clamp is also provided to secure the support frame to the pick up truck.
An object of the present invention is to improve the attachment of the support frame to an inner side-wall of a vehicle.
Another object of the present invention is to maximize and simplify securement of the end plate engagement member to the support frame and provide an end plate engagement member which can withstand greater tension before the engagement with the support frame fails. The integral incorporation of the fastening element better secures the fastening element within the engagement member. The location of the fastening element immediately adjacent to the engagement surface of the engagement member reduces the distance between the surface and the fastening element and torque that can be applied to fastening element when it is securing the engagement element to the support frame.
Yet another object of the present invention is to reduce areas of high stress concentrations in the end plate engagement member.
Still another object of the present invention is to lessen the exposure of the latching member relative to the support frame.
Another object of the present invention is to minimize deflection of the engagement portion of the latching member in response to force exerted by the end plate.
Still another object of the present invention is to reduce inadvertent and/or unauthorized disengagement of a flexible cover from a cargo box of a vehicle.
These and various other advantages and features of novelty which characterize the present invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the present invention.